Mirdula Tyagi

Antialgal activity of a hepatotoxin-producing cyanobacterium, Microcystis aeruginosa

Antimicrobial activity of toxin produced by a freshwater bloom-forming cyanobacterium Microcystis aeruginosa has been studied. When tested against certain green algae, cyanobacteria, heterotrophic bacteria and fungi, the toxin inhibited growth of only green algae and cyanobacteria. The toxin has been partially purified employing Thin layer chromatography (TLC) and High-performance liquid chromatography (HPLC) techniques and appears to be microcystin-LR (leucine–arginine). Both crude and purified toxins showed toxicity to mice, the clinical symptoms in test mice being similar to those produced by hepatotoxin. Purified toxin at a concentration of 50 μg ml−1 caused complete inhibition of growth followed by cell lysis in Nostoc muscorum and Anabaena BT1 after 6 days of toxin addition. Addition of toxin (25 μg ml−1) to the culture suspensions of the Nostoc and Anabaena strains caused instant and drastic loss of O2 evolution. Furthermore a marked reduction (about 87%) in the 14CO2 uptake was also observed at a concentration of 50 μg ml−1. Besides its inhibitory effects on photosynthetic processes, M. aeruginosa toxin (50 μg ml−1) also caused 90% loss of nitrogenase activity after 8 h of its addition. Experiments performed with 14C-labelled toxin indicate that the toxin uptake by cyanobacterial cells occurs both in light and dark. These results demonstrate that the toxin is strongly algicidal and point to the possibility that it may have an important role in establishment and maintenance of toxic blooms of M. aeruginosa in freshwater ecosystems. The relative significance of the hepatotoxic effect and the algicidal effect of the toxin is discussed with reference both to survival and dominance of M. aeruginosa in nature.

Fetal Growth in Maternal Anaemia

The effect of maternal iron deficiency anemia on fetal growth was studied in 54 anaemic (haemoglobin < 11.0 g/dl) mothers. Twenty-two mothers served as controls (haemoglobin > or = 11.0 g/dl). All the women had singleton live births at term gestation. The maternal iron status was assessed by serum ferritin estimation. The birth weight, head circumference, chest circumference, mid-arm circumference, and crown heel length were significantly low in infants born to women with moderate (haemoglobin 6.1 +/- 8.5 g/dl) and severe anaemia (haemoglobin < or = 6.0 g/dl), in comparison to infants born to non-anaemic women. Similarly, birth weight, mid-arm circumference, and crown-heel length were significantly low in infants of women with depleted iron stores (serum ferritin < 10 micrograms/l) than in infants of women with serum ferritin levels of 20 micrograms/l or more. All indices of fetal growth showed linear relationships with maternal haemoglobin, as well as with serum ferritin. The growth retarding effect of maternal anaemia was more on fetal birth weight and mid-arm circumference than on other anthropometric indices of the newborn.

Synthesis of 5- [(11Substituted Phenothiazinoacetyl) Semicarbazidothio-Semicarbazido]-2- Oxo/Thiobarbiuric Acid as Anticonvulsant Agents

2-Substitutedphenathiazine was prepared according to the reported method. Ethylsubstitutedphenothiazinoacetates(1a-1b) were prepared by the reaction of ethylchloroacetate in the presence of anhydrous K2CO3. 2-amino-5-N 10substitutedphenothiazinoacetyl)–semicarbazdes/ thiosemicarbazides (2a-2d) were synthesized by refluxing compound (1a-1b) with thiosemicarbazide/semicarbazide. Compounds (2a-2d) were then underwent mannich reaction to yield compounds 3a-3d. All the newly synthesized compounds (i.e. 2a-2d and 3a-3d) were evaluated for their anticonvulsant activity. Almost all the compounds have shown promising anticonvulsant activity. Compound 3d was the most potent compound of this series. The most potent compound was evaluated for its anticonvulsant activity and acute toxicity.